DESCRIPTION: (provided by the applicant) Overall Objective: Characterize damage modes and failure mechanisms in clinically relevant ceramic-based layer structures, and thereby provide guidelines for the design of next-generation dental crowns. Aim 1 - Evaluate single-cycle, contact damage modes and ensuing failure mechanisms in flat-layer ceramic veneer/core structures on dentin-like substrates Aim 2 - Analyze damage modes in layer systems, as a function of layer thickness, material properties, and interface toughness Aim 3 - Extend study of model layer systems to tests in contact fatigue loading, in selected environments (especially water), to determine the role of cyclic loading in oral conditions.